title: Factors influencing discordant results of the QuantiFERON-TB Gold In-tube test in patients with active TB.
abstract: OBJECTIVE
  Indeterminate or negative results from the QuantiFERON-TB Gold In-tube test (QFT-GIT) for TB-confirmed patients indicate the lower sensitivity of this method. The aim of this study was to determine the factors associated with indeterminate and negative QFT-GIT results in active TB patients.
  
  
  METHODS
  We analyzed retrospectively the laboratory and clinical data of patients diagnosed with TB between December 2009 and April 2012 at a tertiary university hospital in Seoul, Korea.
  
  
  RESULTS
  Among 1301 patients who underwent QFT-GIT, TB-PCR and TB-culture, 168 (12.9%), those with positive TB-PCR or TB-culture were diagnosed with TB. Thirty-nine (23.2%) had indeterminate or negative results by QFT-GIT assay, which did not correlate with positive results of TB-PCR or TB-culture. These patients were older, had lower lymphocyte, total protein and albumin levels, and showed significantly higher CRP levels than the positive group. Multivariate logistic regression analysis showed that the probability of indeterminate and negative QFT-GIT results increased as CRP (odd ratio, 1.069; 95% CI, 1.013-1.127; P = 0.014) or age (1.030, 1.005-1.056, 0.02) increases.
  
  
  CONCLUSIONS
  When levels of markers of inflammation, such as CRP, are high or the patient is older, QFT-GIT results should be interpreted carefully and correlated with additional tests for TB.
authors.affiliation: Department of Medicine, Graduate School, Kyung Hee University, Seoul, South Korea.
authors.forename: You La
authors.initials: YL
authors.lastname: Jeon
authors.forename: You-sun
authors.initials: YS
authors.lastname: Nam
authors.forename: Eunkyoung
authors.initials: E
authors.lastname: You
authors.forename: John Jeongseok
authors.initials: JJ
authors.lastname: Yang
authors.forename: Min Jin
authors.initials: MJ
authors.lastname: Kim
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Cho
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Park
authors.forename: Hee Joo
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000032:analysis; D005188:False Negative Reactions; D005260:Female; D006785:Hospitals, University; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D012189:Retrospective Studies; D062606:Tertiary Care Centers; D014376:Tuberculosis / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D002097:C-Reactive Protein
keywords: Age; C-reactive protein; Interferon (IFN)-γ release assay; Lymphocyte; Tuberculosis